1. Field of the Invention
The present invention relates generally to a suspension control system which is particularly applicable for an active suspension system for performing height regulation and vehicular attitude regulation based on preselected suspension control parameters. More specifically, the invention relates to a system for of monitoring an inertia force a experienced by vehicular body as a control parameter, with high precision, for permitting high precision control of the suspension system.
2. Description of the Background Art
The Japanese Patent First (unexamined) Publication (Tokkai) Showa 63-130418 discloses an active suspension system. In this prior proposed system, lateral, longitudinal and vertical acceleration sensors are employed for monitoring inertia forces exerted on the vehicular body, which inertia forces may affect vehicular attitude to cause rolling, pitching, bouncing and so forth. The system performs suspension control for adjusting damping characteristics of respective suspension systems, each of which are disposed between a vehicular body and associated one of road wheel for damping relative displacement therebetween.
Though such an active suspension system is generally successful in regulating vehicular height and vehicular attitude, a problem is encountered by resonance frequency range of the acceleration sensor employed for deriving suspension control signals. The acceleration sensors employed for monitoring inertia force have a resonance frequency range, for example at approximately 38 Hz. The peak of resonance in such case is about 30 Hz. Therefore, when the input vibration due to road surface undulation and so forth have a frequency in the vicinity of the resonance frequency range, the acceleration sensor output may become greater than that should be. The acceleration data containing error component may make the suspension control inaccurate for causing degradation of vehicular riding comfort and/or vehicular driving stability.